A retroreflective sheet is a reflector that reflects incident light in a direction in which the light is made incident as it is. The retroreflective sheet is processed to have a desired shape and pattern on a body surface in a form of a sheet and attached to a traffic sign or a selected portion of a uniform of a fireman and so on, with an adhesive or through sewing or the like, having enhanced visibility, so as to be easily viewed or recognized even in a dark environment. Thus, when the retroreflective sheet is attached to clothes worn by people, who work on the roads or in a dangerous place, such as sweepers, firemen, policemen, factory workers, construction crew, safety men and so on, a location of a wearer can be clearly recognized by those around, obtaining a great effect in terms of protection and safety of the wearer.
The retroreflective sheet is formed to have a stripe pattern that a reflective region reflecting incident light and a colored fluorescent region are alternated on a base. The reflective region is configured as a light concentration layer formed by attaching beads to a reflective layer deposited with a metal such as aluminum or the like, and the fluorescent region is configured as a fluorescent material layer coated with an organic binder including fluorescent pigment.
FIG. 1 is a cross-sectional view of a conventional retroreflective sheet.
The conventional retroreflective sheet is formed to have reflective regions RA1 and non-reflective regions NRA1 alternated in a stripe shape. In the retroreflective sheet, a bonding layer 13 and a colored layer 15 are sequentially stacked on a base 11, and light reflective members 23 each consisting of a reflective layer 17 and a light concentrating layer 21 are formed to be alternated in a stripe pattern on the colored layer 15. A portion in which the light reflective member 23 is the reflective region RA1 and the other remaining portions exposing the colored layer 15 without having the light reflective member 23 is the non-reflective region NRA1.
The reflective layer 17 is formed by depositing a metal, such as aluminum or the like, having excellent light reflective characteristics on a lower surface of the light concentrating layer 21 including a plurality of beads 19 to concentrate (or condense) incident light, and reflects light.
The retroreflective sheet having the foregoing configuration reflects incident light by the light reflective members 23 formed in the reflective regions RA1 to easily recognize it on its periphery even at night or in a dark area. That is, in the light reflective member 23 consisting of the light concentrating layer 21 and the reflective layer 17, the light concentrating layer 21 concentrates incident light and the reflective layer 17 reflects concentrated light, emitting light in a stripe pattern, whereby the retroreflective sheet can be easily recognized around it even at night with a small amount of light or although it is located in a dark area.
FIGS. 2A to 2E are views illustrating a process of fabricating a retroreflective sheet according to the prior art.
Referring to FIG. 2A, a bid alignment layer 27 is formed on a carrier film 25. The carrier film 25 is formed as general paper or the like, and the bead alignment layer 27 is made of a synthetic resin having viscosity characteristics.
Further, the light concentrating layer 21 is formed by sprinkling a plurality of beads 19 on the entire surface of the bead alignment layer 27 such that the plurality of beads 19 form a layer. Here, the plurality of beads 19 are made of a transparent non-vitreous ceramic or a transparent synthetic resin, and fixed to the bead alignment layer 27 having viscosity characteristics such that they do not move, to form the light concentrating layer 21.
Subsequently, a metal such as aluminum (Al), silver (Ag), copper (Cu), zinc (Zn), tin (Sn) or the like having excellent light reflecting characteristics is deposited on the light concentrating layer 21 to form the reflective layer 17. The light concentrating layer 21 and the reflective layer 17 constitute the light reflective member 23.
Referring to FIG. 2B, the structure in which the bead alignment layer 27 and the light reflective member 23 consisting of the light concentrating layer 21 and the reflective layer 17 are sequentially stacked on the carrier film 25 is cut to have a strip pattern with a certain width RA1.
Referring to FIG. 2C, the bonding layer 13 and the colored layer 15 are sequentially stacked on the base 11, separately from the process of FIGS. 2A and 2B. The colored layer 15 may have a fluorescent function or a phosphorescent function or may have the both functions.
Referring to FIG. 2D, the structure, in which the bead alignment layer 27 and the light reflective member 23 consisting of the bead alignment layer 27 and the light concentrating layer 17 are sequentially stacked on the carrier film 25, to be cut to have the certain width RA1 in a stripe pattern in FIG. 2B, is attached to the colored layer 15 such that the reflective layer 17 of the light reflective member 23 is bonded to the colored layer 15. Thus, the portions the colored layer 15 to which the reflective layers 17 of the light reflective members 23 of the structure cut to have the certain width RA1 in a stripe pattern are attached become the reflective regions RA1 and the other remaining portions to which the reflective layers of the light reflective members 23 are not attached become non-reflective regions NRA1.
Referring to FIG. 2E, the carrier film 25 and the bead alignment layer 27 are removed. Accordingly, the light concentrating layer 21 of the reflective region RA1 is exposed, completing a retroreflective sheet having the reflective region RA1 and the non-reflective region NRA1 confined therein.
However, in the foregoing retroreflective sheet according to the prior art, since the light reflective member 23 is formed only in the reflective region, not in the non-reflective region, a step is formed between the reflective region and the non-reflective region, causing a problem in which the light reflective member formed in the reflective region is easily delaminated from the body. In addition, since the light reflective member together with the carrier film are cut, attached to the base, and then, the carrier film including the bead alignment layer as a light reflective film is delaminated, the manufacturing process is complicated.